1. Technical Field
The presently disclosed subject matter relates to a breast pump for expressing breast milk.
2. Description of the Related Art
A breast pump used by a mother or the like to express breast milk has a horn part that is abutted against a breast, and negative pressure forming means, such as a pump, for creating negative pressure in a space formed by abutting the breast against the horn part. The breast milk suctioned into the negative pressure space is poured into and stored in a bottle. The space formed with the negative pressure is connected with the pump by connection means (see, for example, Japanese Patent Application Publication H11-226117).
Such a breast pump is so designed that a valve body that is accommodated in a housing provided in the connection means is activated by an increase of the liquid level of the breast milk to close an opening that is opened toward the pump side which serves as the negative pressure forming means. In this manner, the breast milk can be prevented from flowing toward the pump which serves as the negative pressure forming means, and thus also prevents rusting and contamination of the mechanical structure. In the case where the negative pressure forming means is constructed not from the pump or other mechanical structure but a manual mechanism such as a lever, the breast milk can be prevented from flowing into this lever and/or onto a user's hand.
However, in this breast pump, the opening that is provided in the connection means and communicates between the negative pressure space and the pump is structured to be closed by the operation of the valve body.
Therefore, because the negative pressure space and the pump are not completely separated in a liquid-tight fashion at all times, there is a risk that the breast milk itself or the breast milk that is formed into a spray by the negative pressure might flow from a small space into the pump, even if/when the valve body closes the opening.
For this reason, the machine parts of the pump may become contaminated, which might result in bacteria development. The manual negative pressure forming means may also become contaminated and unhygienic.
A conventional breast pump is also described in Japanese Patent Application Publication No. 2006-102220.
In this breast pump, a milking part is configured so as to separate a sealed space formed by abutting the milking part against a user's breast when milking (or a space that is in communication with this sealed space) and a pressure changing means from each other in a liquid tight fashion. The milking part has a pressure transmission part for transmitting pressure changed by the pressure changing means, and the pressure transmission part has a deformable part where the cubic content or volume in the sealed space (or the space in communication with the sealed space) is deformed by the movement of the pressure changing means.
Therefore, because the pressure transmission part separates the sealed space formed in the milking part from the pressure changing means (such as a pump) in a liquid tight fashion, the expressed breast milk can be effectively prevented from flowing to the pressure changing means. As a result, the pressure changing means can be prevented from being corroded or damaged by coming into contact with the breast milk, as well as from becoming contaminated and unhygienic.
However, although the breast pump of Japanese Patent Application Publication No. 2006-102220 realizes the structure in which the primary side serving as the sealed space which communicates with a milking space and allows the passage of the breast milk is liquid-tightly separated from the secondary side in which is present a case connected with the pressure changing means, these primary and secondary sides are structurally bonded together.
For this reason, another problem raised is that the bonded structure between the primary side and the secondary side causes inconvenience when carrying, storing, handling, and cleaning.